By Harvard University's Center on the Developing Child.
Phyllis Porter, M.A., highlights examples of how very young infants interact. By Educarer.org., The World of Infants.
Parenting Counts' website provides photos and information on milestones birth to five-years-old organized by physical, social, learning and communication categories. This link takes you directly to the "Developmental Timeline" section of the website.
From Zero to Three, by the National Center for Infants, Toddlers, and Families. Provides tips on how to respond to a variety of challenging behaviors, such as: biting, crying, learning self-control and much more. Followed up by this Q&A page.
Written by Diane Powell, et al. Originally published in Infants & Young Children, Vol. 19 (2006), but made available via University of Washington.
From For Our Babies. Provides information and statistics on quality infant/toddler care.